Bookmark Deletion on my iPhone

I have used Bookmark sync between my iPhone (currently SE Gen3) and HP All-in-One PC for some years via iCloud for Windows. Somehow the bookmarks were corrupted. Easy I thought just use iCloud Recovery - only to find there were no recovery files to be found (very disappointing), only a never ending timer and a statement 'No Bookmark Files'.

I have a set of Bookmarks on my PC (Google Chrome) and want to sync these with my iPhone/iCloud. However I can't clear the Apple bookmarks, only one at a time (!). Is it possible to do a 'Clear All' on my iPhone/iCloud Bookmarks? Note I don't have a Mac computer from which I understand it is possible to undertake such an operation.