Airport time capsule - how to erase old back ups to make room for new

Dear Community. My airport time capsule is full for back ups and so will not back up anymore. I thought it automatically erased old back ups to make space. I note from previous threads that this might not happen in practise because old back ups are only incrementally deleted. I also noted that one option is to manually erase the data on the airport time capsule - but someone also recommended not to. I definitely don't need my old back ups so am happy to delete. However when i open airport time capsule in preferences or in finder I am unsure what to actually delete as I cannot see e.g the size of the back up or a clear name that says back up on X date etc. For e.g is it the 'sparse bundle' I should delete? Could anyone give me a few pointers. Much appreciated.