Real reason: Opposition (CHP) is the first party since the local elections and it is almost certain that Imamoglu will replace Erdogan in the next elections. CHP primaries will be held this weekend and Imamoglu was the sole candidate.
Made-up reason: Imamoglu transfered to Istanbul University from a foreign university (Cyprus) in 1990. They claimed that university was not accredited by Turkish Higher Education Council. That was not really a requirement for the transfer at the time and the universities used to have more autonomy. Today they also annuled the degrees of 28 more people who did the same thing in 1990, just for the optics. I think one of them is a college professor.
I saw an argument about this latter decision which (rightfully) claimed that, if what happened is lawful, then they should also revoke the diplomas of all students of that college professor.
Made-up reason: Imamoglu transfered to Istanbul University from a foreign university (Cyprus) in 1990. They claimed that university was not accredited by Turkish Higher Education Council. That was not really a requirement for the transfer at the time and the universities used to have more autonomy. Today they also annuled the degrees of 28 more people who did the same thing in 1990, just for the optics. I think one of them is a college professor.