If you want to take a minute vs. 10 seconds, just slip a blade, even a putty knife one will do, into the seam between the plug and bar. Wiggle the blade, and work around. Soon you'll have enough of the plug out to pull with a bare hand. Easy, and no chance of damage for anything
This proved to be quite impossible with the Speedymoto bars. The nylon plug is flush fit, has no give, and is incredibly hard. I made more progress cutting into the metal bar than the nylon plug. Needless to say I had made a mess of things, and was practicing some serious anger management.
So, when hand tools fail, the power tools come out and play. The plug met the business end of my DeWalt corded drill. I drilled a hole axially, through the center of the plug towards the controls, then drilled another hole completely through the plug, perpendicular to the first. Slid a screwdriver through the hole and twisted the bar end off. Great success.