Regain Space In Your Gmail Inbox By Deleting Unwanted Attachments!
My Gmail was overloaded i spent hours trying to find a solution for precisely this "delete unwanted attachments but retain the messages"
The tech blogs all say Thunderbird or imapsize, they both kept on crashing on me and then I discovered SlimBox !
This is such an awesome utility and does the job!
It also offers an option to save the attachments locally
Give it a try the beta version is currently free, and remember to buy the devs a coffee if you find it useful!
https://rok.strnisa.com/slimbox/