How do I get her to stop and I wont need to be mean as she tells the teacher everything and I don't wanna be called to the office?

This girl is toxic nd I cant stand her . My parent told me not to talk to her BC she is toxic . She waits for me after lesson. ( this is another girl not the one I was talking about before) she waits for me after lesson which is only one lesson which is only one lesson and so she waits for me so we can walk together to the next lesson which we are in different lessons . After that she has geography and I have maths so we walk together but there is no point and plus I cant stand her so how am I supposed to stand her whilst we walk together for like 10 seconds.i don't want to wait for her but then she will ask why and I wanna say the same " bc ill be in a hurry to get to my lesson") and then she will say " well we always walk together " and then idk what do say and plus if I say " bc ill be in a hurry" she will keep bugging me then im thinking of saying the same " no now stop asking me " so remember she tells the teacher everything so is it a bit stupid to tell off me for and will she tell off me for that . Will I be able to say that safely without her going to a teacher