Some laptops permit operation with the battery removed from the battery bay. In addition to stopping charging, it prevents exposure to potentially damaging heat—heat is the main contributing factor to premature failure of laptop batteries. Both of my laptops (HP Pavilion dv6z-3000 and Clevo P157SM) can run without a battery attached. To test whether this can be done safely, turn off the computer, remove the battery with the AC adapter plugged in, and try turning it on. If it turns on, you should be OK.
Some laptops may not be as well-behaved when you do this, with reduced performance when the battery is removed especially if the AC adapter can't supply enough power for full-load operation (such as when gaming). While neither of my laptops do this, this is worth noting.
Be sure to put the battery back in before you unplug, though!