What should I do with my denim jeans that I fear might be misused if I give them to someone else?

It is permissible to wear wide trousers that do not reveal the 'awrah (private parts) and do not imitate the polytheists, and similarly, it is permissible to sell them and dispose of them. However, if they are tight and reveal the 'awrah, or if they involve imitation of the polytheists or the wicked, then it is not permissible to give them to anyone. It is better to utilize them for a permissible purpose instead of destroying them.