Erase and Transfer Sim Card

Hello! The company I work for purchases iPhones through Verizon, and recently I have noticed an issue that I was wondering if you could help answer. We are constantly buying new phones, and all of them come with a sim card. However, we have ended up paying for a bunch of inactive lines because we place a new sim card in the phone if we switch device owners for security reasons. This means that, due to Verizon's early termination fee, if an iPhone changes users before the two years is up, we are stuck paying for a dead line each month. Is there any way (preferably NOT a third party) to erase all content on the sim card? I know iPhones don't store much on the sim card, but we would need complete erasure of all content and settings. If we could erase the sim card data, we would then be able to transfer the phone to a new owner and keep the same number rather than opening a new line. Thank you for your help --I really appreciate it! :)