Delete / Reinstall Garmin Maps

I had a failure noticed during an attempted update of my Garmin Topo maps (Europe). While mapping still works it is super slow now and I only have one European map (seem to remember that the Europe map files are split into two parts) and the base map. In addition starting up the F5+ takes approx. 90s and it is hung at the "loading maps" screen. 

To debug things I would like to delete my Garmin map files and re-install the maps from Garmin. I am aware of Talkytoaster & friends but for now Garmin will do. 

What's the recommended procedure to re-install Garmin's map package?

Cheers

Chris