How can I delete all bookmarks in Safari at once on iOS

Do you have a Mac? If so, you can sync your Safari bookmarks via iCloud and manage them from there. On the Mac, open Safari - Bookmarks, select the first bookmark, hold down Shift, then click the last one to select all—hit Delete, and they’re gone.

Unfortunately, iOS doesn’t have a way to delete all bookmarks at once—you’d have to remove them one by one.