How can I delete mailbox on my Nokia C5 device?

Depending on how you have created mailboxes perform the following:

Open Menu > Messaging > Options > Settings > E-mail > Mailboxes and then long press on mailbox opens the selection to delete it.

Or select Menu > Applications > EmailOptions > Tools > SettingsHighlight the mailbox you are deleting > Options > Remove mailbox.

Applies for Nokia C5-03, C5-05 and C5-06 phones.