If you have the extreme upgrade, you can edit sites from the radio. When the system is actively receiving, right click under advanced.
Go to site information.
All sites fo a system will show. If all are active they will be colored.
After clicking on one, it show info about that site and 2 options. One to look at the frequencies and another to avoid the site.
This will gray out the site and it will no longer be scanned.
You can also just create systems with just certain sites and then turn off or on by selecting favorites lists. Without extreme option, the second method I'd yhe only one.
Mark
536/436/ws1095/996p2/996xt/325p2/396xt/psr800/396t/HP-1/HP-2 & others