I did /summon with this "entity.trajanscore.example_tank" and once I hopped in it nothing happens, the tank is stuck to me, I can't press shift to get out, press e doesn't nothing, I can't switch items and even /kill does not get rid of it. Even I disabled the mod and the effects continue. What do I do?

Please tell us the minecraft version and mod version. And this usually does not happen. You need to elaborate more.

I forgot I had this open but sadly I forgot about that stuff since I removed the mod and had to delete the world,