You accidentally placed 4-cycle oil in your 2-cycle-engine weedeater There is still some in the tank Should you remove it or just use it this time?

You should remove it. 4 cycle oil does not burn the same or adequately lubricate the bearings of your 2 cycle engine. You risk experiencing an engine failure on your 2 cycle engine if you continue to use it. If you are concerned about wasting the mixture, pour it into your car when the tank is nearly full. That engine will never notice the difference