Mac running very slow

I'm not sure who I need to contact for this but my Mac has recently been running very slow. Its to do with me having caches which are not deleted or files/apps taking too much storage. I probably can work out how to do it on youtube and make it faster but if there is anybody out there who can do a team viewer session and help me to do it quicker and properly im happy to pay them! this is a quick job I assume that might take 15-30 minutes or so and so im happy to pay £30. hopefully that is reasonable?

thanks