Ummm, this not how it works. The GPS is used with one or more favorites lists and/or full database, that have location control and lat/long/range established for the site/channel. The gps feeds location of the scanner to be used when evaluating the above and guides decision on what to scan. The "what to scan" list gets reevaluated as you move on down the road and "re-programs" the scanner on-the-fly. Nothing gets locked-out per se.
Location Control and GPS doesn't use the Avoids you set or clear manually. It's all internal. The scanner periodically compares its location to the locations programmed for scan items, and will automatically update what is scanned as your location changes.