Read the description on the toy. Most will give a clue or more for removal, or...
In the Toys&Love MCM, Worn Toys Tab, click on the toy to view the detail. Look at "Escape methods"
Cheat Method: Toys&Love MCM - Worn Toys Tab, click on the toy to view the detail. Debug option to remove OR use the cheat method on Last Tab
Getting Keys
Install the ToyFul Temptations mod (Toys Family of Mods for link), it will put Toys Keys in the world to be found. That's the Default way to get Toys Keys.
Note: If you are adding the ToyFul Temptations mod mid-playthrough, follow the golden rule (you can do so by placing it at the end of your load order). Otherwise, you will corrupt your save.
Transforming Toys
Some toys cannot be removed till they have "transformed". Only the transformed variant has removal options. You can see if the toy transforms the MCM detail view. Transforming toys always have a clue for escape in the description
Self Bondage
If equipped manually by the player it's "self-bondage". The MCM Setup Tab has a setting to make self-bondage always unlocked