How would I make a NoPlayer Collision?

I want to make a NoPlayer Collision that can be toggled in game on/off. For example maybe If I press a button I will be able to collide with players, If I click another one I will not collide with them.

Or.. maybe a command to type in-game?

You should look into PhysicsService as it explains everything you need to know: https://developer.roblox.com/en-us/api-reference/class/PhysicsService

Here's an example: https://developer.roblox.com/en-us/articles/Player-Player-Collisions

Hope this helped.