18650 Battery Replacement. How can I put/connect new batteries to these cables?

the title is relatively self explanatory, I brought a cheap £5 handheld vacuum off of Temu, no issues with it but I wanted to have a faster motor, better impeller and larger batteries. These cells are 1500Mah each and I've brought a pair which is 3500Mah each, same voltage. How would I pull these ones off and put the new battery on? I'd assume I can't solder them on?