I've just bought a second hand mini Heki, which came as removed, so still with the black sealant on it.
To clean this off I scrapped the bulk of the sealant off with a screwdriver and then with the sealant a ball of them sealant press this onto the remaining sealant and snatch up.
Doing this the sealant sticks to itself more and should come off the frame.
This took about 45 minutes to remove the old sealant and no solvents used.
To clean this off I scrapped the bulk of the sealant off with a screwdriver and then with the sealant a ball of them sealant press this onto the remaining sealant and snatch up.