Maybe I missed it, but I cannot see an y of your items in auction format.
If it is there, and has more than 12 hours to run simply end it and relist back in a Buy it Now format if that is what you wish to do. If there are any bids, you will pay a seller fee based on the highest bid placed, for ending the auction early, eBay see it as disappointing their buyer.
Reserves are optional listing ugrades , and used for very expensive items, hence the minimum you can start with is £50.
You don't have to use reserves , just start auctions for the lowest amount you are happy to receive, it cannot sell for less.
@cy981424