Putting items in your cart alone does not commit you to purchasing; that requires additional actions.
If you have not committed to purchase those items yet, you should be able to remove the items from your cart. Either using a "remove" link by each item, or by swiping the item left if you are using the eBay app.
If you requested a total from the seller using the "Request total" link in the cart, that would commit you to purchasing those items, though. Placing a bid on an item and winning the auction commits you. Making an offer that is accepted or accepting an offer or counteroffer commits you. Using the buy-it-now link and going through checkout commits you.
