The top of '去' looks like a 'soil' (土) mound, and the bottom looks like a 'person' (人) or a bent leg kicking off. Imagine someone kicking off the earth to 'go away' or 'leave'.
'KO' — sounds like 'GO away!' to remember the meaning 'go away'.
'SARU' — sounds like 'SAIL away!' which is a great way to remember 'to leave' or 'to go away'.