So do I just take the tardis stuff out of the worlds folder and that's it or is there additional steps that I have to take cause I did a lot of work on this Tardis and don't wanna lose it 

Hi, if the TARDIS is in a singleplayer world and you wish to change to a different update then you don't need to do anything, the world will still exist. This only works if the update you're changing to is in the same Minecraft version