You can omit "that".What I'm wondering is the use of 'that' in the below sentences.
1. You can leave anytime that you want.
2. You can leave at any time that you want.
3. You can sit anywhere ( or anyplace) that you want.
4. You can sit at any place that you want.
Will it be safe to tell my students that all of these sentences are grammatical?
Will it be okay to omit 'that' in the above sentences?
Also, I wonder whether 'that' in the above sentences is a conjunction or a relative pronoun.
Thank you so much.