!MB isn't very large, did you typo and mean 1GB?
The only mass removal of attachments is all or nothing and that is done using the File Copy process on the File menu.
Regarding keeping your receipts in Quicken, most of the regulars here on the forum discourage it for the very reason that you have at the moment with file size and the inability to do anything with them in mass. Keeping scanned receipts is a great idea, but I would find a scheme using some sort of folder structure to store them elsewnere on your computer.
You can get rid of them in mass, but it is all or none. If you make a copy/template file the is a checkbox to include/exclude the attachments from the copy. Note that the copy will have all the online services disabled.
File → Copy or Backup File → Create a copy or template