How can I free up capacity on iCloud? - I only have mail on it!

The only thing sync'ing is Mail!

I only need current/recent e-mails available on all devices. This would free-up capacity in my iCloud. I would feel more secure about this too. Why am I forced to purchase capacity I do not need if only I knew how to manage this mail folder.

Is this what "Archiving" is?? I never archive anything because I don't know where it goes! -laugh Please help me out.... I have deleted a number of e-mails but it doesn't seem to budge the capacity. ... how do I eliminate all attachments in file - surely I do not need them. ~ Thanks in advance, Dana

iMac 2007 - 2.4 GHz Intel Core 2 Duo - 3 GB 667 MHz DDR2 SDRAM - 35.14GB Free of 319.21GB

iPhones: 6S, 5S, 4x2, Ipad2x2 and a MacPro-I think its called. laptop