PLEASE HELPPPPP

So I have an early 2015, Macbook Air, 13in, and for a few years I didn't use it but for maybe streaming sites for shows and basic internet searches after I graduated college in 2017. Currently I own my own photography business and am back to putting some use in. It needs to be updated, as it stand at the OS X YOSEMITE 10.10.5, but says I don't have enough space for the newest update. I've literally deleted anything and everything off of it, with 30.39 GB of space available of the 121 GB. What more can I do or is it a lost cause?