GMforPowergamers
Legend
They don't take away all their magic. Multiple examples show this. I don't know where you're getting that from.

Towers of High Sorcery
The Towers of High Sorcery were built as places for Wizards of all three types of High Sorcery to come and study. The Towers were built by having three wizards, one from each order, come together with a Stone of Threes on a pre-selected site. The pre-selected sites originally were Wayreth...

Test of High Sorcery
The Test of High Sorcery was created by the first Three mages, Corenthas, Eriane, and Shaud, in order to make sure that those who did not have self-control did not have access to High Sorcery. Those who wish to take the Test, must first be apprenticed to one who is a master in magic. Once the...
here you goAfter the apprentice has been invited, they will travel with one companion to the Tower of Wayreth. The Wayreth Forest will find them, and allow them to continue on to the Tower. Once there, they are given one day to prepare, and the Highmage will erase all the memories of magical training.
the Highmage will erase all the memories of magical training.