Is there anyway to terminate the LOL client?

A few times now during ranked games LOL has frozen, if I have any break in my internet it freezes and stops responding. There is no way I can terminate it then. The only way to restart LOL is to restart my computer by which time the game has ended. I can open task manager but I can't focus it. Anytime I try to click it LOL appears back full screen even though it is not responding.
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