Aiding in Sin

Q: I am a lecturer/ tutor by profession. A lecturer asked to use my lecture theatre time for something. I did not understand or listen to her properly what she wanted to use the lecturer theatre for. Without listening properly I allowed her. Later on, i realised it was for Holi celebration and Easter celebration. Have i committed a sin? What do i do to ask forigiveness from Allah on this? But then again, it was not entirely on me allowing it or no because that lecturer threate is owned by my employer but I was only scheduled to take a class during that time.

Q: I wanted to know what we should do with TV(s) we no longer want to keep in the house, alhumdulillah the usage of TV has reduced considerably in our house and I wanted to know can we sell the TV or do we need to break it and throw it away so no one else can use it, and we cannot be held accountable for others sins due to them watching the TV?