Deleting themes in WordPress has a couple of benefits. For one, it can allow you to save money. Some hosting platforms charge you for the amount of data that your website uses on their servers. When you have several inactive themes on your website, this can mean that you are being charged for useless memory usage.
Another reason is that it is better to manage a couple of themes on your website than dozens. It means that when you have an update, it is for something that you need or might need.
It is important that you don’t just want one theme on your website. If there is an error on your website, it is useful to have a backup theme on a website.
You might also want to delete themes that have not been updated in a long time. This makes
them easy access for hackers and a threat to you.