[header] How to remove a stripped screw [title] Maximize the grip strength. [step] If you can still grip the screw head with a screwdriver, try one last time to remove it by hand. Follow these instructions first to maximize your chances : [substeps] If the screw is fastened to metal, spray on penetrating oil, such as wd40, and let sit at least fifteen minutes. 
Use the largest manual screwdriver that fits your screw. If possible, grip the screwdriver handle with a wrench to get more leverage.