Yes, you may withdraw (Verzicht nach Einschreibung). You have to fill out the form "waiver of enrolment" and you may also claim a refund. Mind the deadline and note: the amount refunded will be reduced by an amount depending on the course you enrolled to and if the student ID card (TUNIKA) has already been printed.

The PORTA-System of Trier University is your personal portal which you will use throughout your studies in Trier. 
In order to apply at Trier University, you first need to register in PORTA, and follow the instructions.
PORTA has numreous functions that you will need during your studies, like signing in or out to lectures, registering for exams, downloading certain notices or updating your personal contact information. 

⇒ application period starts usually in the beginning of May for the start of studies in the winter semester (starts Oct. 1st)
⇒ application period starts usually during December for the start of studies in the summer semester (starts April 1st)

When the application period starts, the portal PORTA opens and applicants can register. When finishing the registration, the applicant can print out the request for enrolment (or for admission restricted courses the "Bewerbungsantrag"). This document, along with all your certified documents/certificates, as per checklist out of PORTA, needs to be sent by post to Trier University
The deadline until when your Post has to arrive at Trier University, depends on your nationality and the course you chose to apply to.

International applicants generally need to send all documents per post and within the deadline to Trier University. Note the checklist for international applicants.
German applicants for admission free courses only have to provide their documents for enrolment purposes at Trier University.

Exception: German applicants without German Abitur, applicants for an admission restricted BA course who already studied at an University, or applicants for an admission restricted MA course. You need to send all the documents as shown on the checklist from PORTA by post to Trier University.

The certified copy of a document is the official attestation by a notary or authority, that the copy corresponds to the original document.

Only send your documents, when you already registered in PORTA and printed out the request for enrolment (or the "Bewerbungsantrag" for admission restriced courses). Without this request the application will not be processed.

Universität Trier
Studierendensekretariat
54286 Trier

Germany

First you need to register in PORTA, and then, together with the request for enrolment (or in case you want to apply to a admission restricted course with the "Antrag auf einen Studienplatz") send your certified documents according the checklist via post to Trier Universität.

Depending on your nationality different deadlines apply.
Please check, prior to applying, if your school/University is accredited via the Database Anabin.

No. If you want to apply to a German taught course, you need to hold a German proficiency certificate of level B2 minimum. If all other requirements are me, we invite you to the DSH test (conditional admission), which you need to pass at least with DSH 2 in order to enrol at Trier University. 

Applicants who can provide these language certificates do not need to participat at the DSH test.

No. Trier University does not cooperate with Uni-Assist. Therefore it is neither necessary nor helpful to provide any documents to Trier University that are related to Uni-Assist. To start your application at Trier University you need to register in PORTA.

All students at Trier University pay each semester a semester fee. This semester fee is not a tuition, but rather supports other elements of student life.

No, Trier University does not ask for an application fee. 

Only for the evaluation of international school and/or University degrees Trier University asks for a evaluation fee.

In order to evaluate international school and/or University degrees Trier University claims an evaluation fee. An application with international diplomas will only be processed, if the evaluation fee as been paid and all necessary documents have arrived complete and within the deadline.

The evaluation fee only applies once, also if the applicant applies to multiple courses.

You need to tranfer (by bank) the money to the following account. For both fees the same account applies. Note that you might face extra fees on your side. We cannot offer other methods of payment like credit card, paypal etc.

Receiver: Landeshochschulkasse Mainz
Account Iban: DE 22 5451 0067 0228 1556 76
Reference: Universität Trier 6401 8700 38921, Applicant ID xxxxxxxxx, name, Date of birth dd.mm.yyyy

More Information on the evaluation fee 

More information on the semester fee