your roommate?
Unless you are also their landlord, your notice is meaningless.
so do you own the house (or whatever) or are you the prime tenant having a lease between yuo and your landlord and have sublet to this roommate?
or are you co-tenants on a lease?
never mind; I see you have another thread with that information.
no, you cannot touch their property. After the time of the notice expires, if they have not paid, you get to file an unlawful detainer action with the courts. Then, at that hearing the judge will determine if the tenant has to leave the premises. Then, if the tenant doesn't leave you get a writ of possession and have the sheriff serve it and boot the tenant and their property out the door.
so, until the sheriff shows up, you cannot do anything with their property and their room. You definitely cannot relet the room until the current tenancy has been terminated.

