How Do I Delete A Specific Map From A Garmin Oregon 450?

[photohiker]

How do I delete a map from my Garmin Oregon 450?
A couple of years ago I installed the Montana Topo map from this site. There is now a new version called Montana Topo + National Forests 2015 Map.
I would like to replace the older map with the new Montana Topo + National Forests 2015 Map. How do I delete the older Montana Topo map?
Thanks!

[Boyd]

Before doing anything, make a full backup your your Oregon. Just create a folder on your computer and drag or paste all the files on your Oregon to it. This will allow you to revert if you delete the wrong files - and is a good thing to have for the future.

Now look inside the Garmin folder on the GPS. What files are there? Files with an .img extension are maps. IIRC, on the Oregon 450 the only standard maps would be the basemap (gmapbmap.img) and timezone map (gmaptz.img). If you used MapInstall, any other maps should have somewhat descriptive names. The file modification date should also give you some clue as to what they are.

If you used Mapsource, then the map will be in a file named gmapsupp.img. However, it is possible that this file can contain multiple maps, depending on how you performed the installation.

If you have a memory card in the Oregon, it can also contain maps inside a folder named Garmin. Once you have located the map you want, just delete it.