How do I delete sublemental TOPO maps from Nuvi?

I would love to know the awnser to this one, I am in the same boat. I want to move all my Topo maps to a SD card to speed up loading time when I don't need them. Not sure how to delete all of them, but in the meantime you can just use mapsource to select 1 topo map and send that to your device. It will overwrite all of the previous mapsets, it my case about 120, with that one single topo map. Not a fix of course, but it will let you get some memory back.

Mapsource will have created GMAPSUPP.IMG in the \Garmin directory.

If you are certain you can re-create this mapset, then you can just delete the file.

Fox858's suggestion will work as well - in this case, Mapsource will overwrite the file with a smaller version.

And how to get Those TOPO´s to SD card? I have original map CD's. Should I use Mapsource?

If you're happy with the mapset you've already built, you could just copy it (GMAPSUPP.IMG) off the Nüvi onto an SD card (Make a \Garmin directory on the card).

Or, you could use Mapsource to build it again, direct to the card.

The SD card can be in a dedicated card reader, or accessed via the Nüvi.

I learned this on my old Garmin GPS III+ (which I still have and use while hiking). It works on my Nuvi 660 as well.

When you transfer maps using mapsource, the first thing it does is delete the old map sets. Pull the serial cable out right when it finishes deleting the old maps but before it starts transferring the new maps. You’ll get a “lost connection” type error, but that is expected.