There is a drilling in the side of the plug in which you can put a size 3 Allen key or a Torx key T10 (usually found in the your BMW toolkit) in order to fit and remove it.
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Also referred to as oil filler cap.
These aluminium parts cover the big holes above the foot...
These handlebar risers for your BMW R1250R let you sit up...
These covers for the open holes of the suspension mounting...