The Reading List feature on Safari is handy for saving webpages that you want to read later. Moreover, your offline reading lists are synced via iCloud to access them from whenever you sign in to your account.

BUT saved pages take up space on your devices, so you should clear up your Safari Reading List from time to time. It's not the same as clearing the Reading List cache. Also, bear in mind that changes made on one device will reflect across all other connected devices.

A shortcut: Open Safari ➜ Tap on Bookmark from the bottom of the screen ➜ Select Reading List tab and tap on Edit ➜ Choose entries and then tap on Delete.

See it in detail:

Step #1. Open Safari ➜ Tap on Bookmark from the bottom of the screen.

Step #2. Select the Reading List tab and tap on Edit.

Step #3. Choose entries and then tap on Delete.

These entries will be removed from your Safari Reading List.

NB! The procedure also removes the entries from all devices with your Apple ID, and Safari sync is enabled.