If Epic do not provide a way to do it in their account page or client, then it can't be done I'm sorry.
Frankly it seems unlikely disabling DLCs will help your problem though; FYI they are always there whether enabled or disabled or unbought.
Please gather both these two informational files, and attach them here:
DXDIAG is a program you run from the Windows search box on the task bar. After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.
[Epic location]\Cities Skylines\Cities Data\output_log.txt