I doubt if you will have a usable database if the restore fails, so there is really no point in not dropping it.

FYI, if you set a database offline and online again just to disconnect users, it will be owned by the login that set it online.

if you are doing that, I suggest doing it this way:

execute as login = 'SA'; -- or the login you desire

use master;

alter database [MyTestDB] set offline with rollback immediate;

alter database [MyTestDB] set online with rollback immediate;

revert;

-- or you could do this after setting it online

use [MyTestDB];

exec sp_changedbowner 'sa'