It is possible to edit lead details in Smartlead.
To do the same you need to go to: Campaign>>Lead List>>click on the pencil icon below the lead name/email. (Hover the cursor on the lead name)
**Only the following details can be edited: First Name | Last Name | Company Website | LinkedIn Profile | Company Name | Phone Number.
However, the lead email address can't be edited once uploaded and the campaign is active.
Once the campaign is live, no further updates can be made for the lead.