If you want free deformation like in Worms this is a bit more complicated and you might want to recreate something like this: XNA - Creating games: 2D Deformable Level
If you want to make something simpler for a beginning I have a very old project made for a game jam, where you can “deform” tilemap by removing certain tiles. It’s very primitive, though: Water sources [open source]
What you want to achieve in the end is not only drawing custom shapes and modifying them in runtime, but also do the same for collisions, so that you can put “worms” around and they can move, interact with the destructible terrain.
Similar topic: Destructible terrain (like Worms)
Unless someone is humble enough to do and share all the work behind it is is not something that there is any plugin out for this just to use, it’s too complex and can be achieved in many ways, like it’s actually making a game 
Some related topics you might find on Internet too: physics - Destructible Terrain like worms - Game Development Stack Exchange