Closing the SkyrimTogether UI (STRUI) makes it reopen
Q: When I'm trying to close the STRUI, it just reopens
A: Instead of Right CTRL, try using the F2 button.
A: If that doesn't work, reload your savegame and/or restart your game. It may be necessary to restart several times.
A: If you're using ModOrganizer2 (MO2), you can also try deleting everything in MO2's overwrite folder, which can be found here:
C:\Modding\MO2\overwrite