I soak my system in solvents for 20 minutes and then use a credit card to scrape off the glue.
After that I rinse, wash, comb and allow them to dry naturally.

The solvents I use are not traditional hair replacement specific products.
I use Autoglym Intensive Tar Remover or SX Siroflex Solvent Cleaner.

Both melt the glue thoroughly and leave the system squeaky clean with no residue.
I use them on lace or skin systems.