E Way Bill of mistakenly hold by the transporter

A sent goods to B of Rs. 5 Lac from Arunachal Pradesh to Kolkata through a transporter. But the transporter kept the goods for 1 month in Guwahati, Assam warehouse. Now B says he doesn't require part of the goods.

Now what is the procedure to get back the part goods from Guwahati Warehouse to Arunachal Pradesh and how to sent the remaining goods from Guwahati Warehouse to Kolkata.

How the E-way bill will be generate?