Teleporting doesn't work without the mod because of the way the mod works. It disables teleporting everywhere, all the time, so it can take over from the game and give you multiple teleport marks, and teleporting stays disabled when you remove it because that's the way the DisableTeleporting function works.
To restore teleporting without the mod loaded, open the console and type:
and hit enter.
FYI: You should always be able to leave marks in exteriors, just not interiors. Other than hardcoding each interior (which is what that mod does for vanilla interiors IIRC) - the only way to do that is by using MWSE. If you do run MWSE, I have a mod that provides multiple teleport marks (PES link in my sig), and so does CDCooley's Improved Teleportation (search author CDCooley on Nexus).
PS My mod will do the same thing if it's removed, and I totally forgot to put that in the readme. I'll make a note for the next update. So thanks for reminding me of that