A user had this question:
"I have 4 Exchange accounts set up in Outlook 2010. Only one account is used for mail, calendar, contacts, notes, tasks; the other accounts are only used for email. My Outlook tree is cluttered, duplicating all folders for the 4 separate accounts. Is there anyway to remove the calendar, contacts, tasks, note etc for the accounts only being used for e mail ? Can I merge the in, out, draft and sent boxes for all 4 accounts into 1 set of boxes, although this defeats the purpose of having separate mailboxes…"
If you have the Exchange accounts opened using Outlook 2010's multiple account feature and they are all on the same Exchange server, you could remove the extra accounts from your profile and add them to your main account as secondary mailboxes. You'll need to have the permissions on the extra mailboxes changed so your default account only has read/write access to the Inbox. Add them to your account using the More Settings button, Advanced tab in account settings. To send from the other three addresses, you'll need Send as permission on the accounts and you'll need to type the address in the From field when you need to reply or send new messages from one of the other addresses.
If you need the convenience of Outlook 2010's multiple Exchange accounts, create new groups on each navigation pane and move the unused folders to the new group. Collapse the groups to hide the folders. Add your mail folders to the Favorite folders list.
While it's possible to delete the folders using MFCMapi, Outlook will eventually recreate the default folders. I don't recommend doing this.
My recommendation: If you will be replying or sending new mail from the extra accounts, keep the separate accounts and hide the unused folders in groups. However, if are only reading messages in the other mailboxes, then adding additional mailboxes to your own account works well.