you can sell your towers by right clicking them before starting a wave! I cant blame you for not noticing, it should probably have been in the information menu, considering you're not the first to ask to add selling lol
We really tried to add a proper restart that doesn't delete the towers without making you get extra money or anything but due to time issues and the difficulty of adding that (at least from my pov) this was the best we could do to prevent bugs and unintended behavior
