If the Author gives me the permission to use his/her Admin Template for my Web Application, Can i sell it on CodeCanyon?
If not., Can i sell it using the Author’s account? (with Author’s approval ofcourse)
if its approved by the original Author than yes you can, look at some of the theme forest templates that the html and WordPress themes have different authors
EDIT : So just cleared this up, you would need either the Author’s permission or an Extended License
(Extended License) ...(f) You may incorporate the Work in a work which is created for Resale by you or your client (provided that only the complete work is offered for sale and the terms of sale (i) require those that acquire the work to only use the Work for their own personal use or in a work they are creating for a client (ii) prohibit resale of the Work as a stand-alone item).
You can read more about licensing terms here.