Copyright of a thesis as well as of all other publications always belongs to the creator.
On these pages you can choose a copyright license for your thesis.
If you have not read the instructions for the input and publishing process, you should start by reading them here

With the license chooser below, you can choose a license to your thesis or you can choose to reserve all rights to it.
After finishing this process, you will receive the license information and a link
to the permanent URL for your theses.