I think most people might like cheque back rather than trust stranger has torn up. Not saying you not honest but this client might prefer to have their cheque physically in their hand to have peace of mind it not going to hit account as a surprise withdrawal.
Maybe ask if she want to come and get cheque or if she okay with you destroying it.
I wouldn't be waiting around on her anymore. She messed about a lot and even if she decides normal hours okay, I not sure it good match. Continue advertising, not contact her and if she contact you, see if she want to come get cheque or trust you to destroy it.