Put them in the freezer then break it off when it is frozen. Nail varnish remover will also soften it but it might damage the clothes if they are synthetic .
Many a time over the years I’ve got Debor on my jeans and sweatshirts and what won’t pick off when cold or frozen will eventually wash off after a few cycles in the washer anyway.
I normally use the nearest thing to hand. A good spray of WD40 to get the bulk of it off. That’s if you’re lucky enough to spot it while it’s still sticky. The rest normally brushes off when it’s dry.
Dont want to steal your thread but on a similar line most of my black work t-shirts have had silicoln glue on them for years, (normally when I have done a tub job and lift the drum up to fit it back into the cabinet).
How do I get rid of this?