1999 Speed Triple Oil Leak

Hi all,
I have a 1999 speed triple which has developed a slight oil leak it appeared to be coming from the oil drain plug but after further investigation I have found a 8mm bolt with a copper washer fitted to it on the left side of the engine (see attached picture) which appears to be the culprit it seems to be leaking from this bolt and running down onto the sump then dripping from drain bolt ,I have checked that the bolt is tight .My problem is I'm not sure what this bolt does and is it safe to remove it to fit a new copper washer or is something it's holding going to fall off inside engine any ideas guys .Have thought of a good degreasing and a dob of silicon but would prefer a proper fix (it's the bolt next to the oil pressure switch)

Help Please
Mick G.