If you can handle some basic HTML, then...
Hit Ctrl-Shift-O in Chrome to go into bookmark manager
Click on the three dots up in the top right, and export your bookmarks to HTML
Open the file you exported (after taking a backup!) and modify at will
Go back into Chrome bookmark manager and delete everything
Import your modified export file.
If you manage to screw it up, re-import the backup you kept and try again.