How do I organize my mail accounts in an uncluttered fashion?

Good afternoon tallsweet,

Welcome to the Apple Support Communities!

It sounds like you have 7 email accounts and you'd like to organize and delete the email messages they contain.

Before attempting this project, please make sure you have a Time Machine Backup of your computer.

Back up your Mac with Time Machine

There are a number of ways to approach this. One way is to start with the Inbox of the email account that you use the most.

• Sort the emails by "From" to group the email messages by the sender.
• You can quickly select a "range" of emails this way to delete the email messages you no longer want. (Be sure to empty the Trash in the Mail app when you are through.)
• You can create mailboxes saved on your Mac to organize the messages. An example would be "Receipts."
• You can create folders outside of the Mail app on your Mac and save individual email messages and/or attachments to the folder by using the File > Save As command.
• You could also create a Note for each of your most important contacts or projects. If you open an email message and choose the "Forward" command, you can copy whatever specific info you need from an email (ie. date, subject, and key phrases or sentences) and paste that info directly into the Note.
• Repeat the process for each of your Inboxes, and the "All Sent" mailbox in the Mail app.

The resources below will help you address this issue:

Create or delete mailboxes in Mail on Mac - Mail User Guide

Save emails as files or PDFs in Mail on Mac - Mail User Guide

Notes User Guide - macOS Big Sur

Take care.