I have Fruity Loops studio 10.
I've got a little problem with it, I can't manage to erase tracks of the mixer.
As said earlier, you can unlink a track from the mixer channel. In FL Studio 12, there's a number next to the plugin. You can click on it and scroll all the way down until 0. Then, it'll be unlinked from the mixer track. https://gyazo.com/df19c6273993d6e395e1b1a9369b932c
You can also default a mixer track if you have any existing plugin FX and it's too tedious to go one by one and take them all off the channel. At the top left of the mixer, there's an arrow. Click on it, go to File, Open Mixer State, and load "Default.fst" to start with a clean mixer insert. https://gyazo.com/b6f7df27f12d3179ea9f7829c9db1202
You can also create your own mixer inserts to save for later use and quickly load them to save lots of time!