so salvaging these gives stabilizers.
you can salvage your weapons that are untradable to, even the decor and itll give you some extra stabilizers depending on the rarity. so if you have to many of these items just salvage them and get some extra cash for when they release the event to trade stabilizers again.
And don’t forget to craft the higher-ps stabilizers from the lower ones to reap bigger profits!
a Helpful link… 
How do I salvage my stabilizers?
You can’t salvage them, but you can sell them. They usually have an event that lets you do this about twice per year.
I would and always have had the desire to delete untradeable items I no longer want. never the less they don’t take storage space but a list of stuff you have to scroll through. More of an annoyance speaking of stickers…