Question about saves?

Not sure what kind of saving method you use. It probably matters if you make a completely new save every time you play, but not if you use the Saver method of cycling through four saves and only occasionally make a completely new one.

Deleting the nhd files of worlds shouldn't really matter if you never go back there again.

I would actually concentrate your efforts on your current save. Using Kuree's Save Cleaner can easily cut your file size in half if you've never used it (you can use it on every nhd file). Of course, you should always keep the inventories of sims in your town almost empty and generally go through town to see what you can get rid of to make save times more bearable.

I have deleted multiple destinations world, university world and have no issue with my saves even after I went back to the said world, but if you delete them, every time you go back to this world, it will be as if you haven't go there, all the townies are refreshed (all sims are still in university and none have graduated, tombs are refreshed, etc).

But don't delete oasis landing nhd as that will mess up Emit Relevart npc.

Yes, I deleted that confusing stuff from my last post. With the NRaas mods in place, it's sufficient to have one or several "clean" saves before you go back to a world you have formerly been to. They will usually clean out all relevant data and remove your NPC relations. That can come in handy.

Thanks for the help! I deleted the worlds I don't use and run the cleaner and my folder is almost half the size and the game seems to be loading faster, but there's still the travelDB file which is massive and takes up most of the space (350/500). Any idea how to clear that down as well as the cleaner won't open it?

Use this guide https://sims.fandom.com/wiki/Game_guide:Reducing_the_size_of_a_saved_game

Also disable the memory if you haven't done so, I have traveled to almost 9 different worlds in my currnt saves and none of my traveldb file ever reaches 100mb.