Batch file

If anybody could help me with the following batch file code I would appreciate it.

I connect to two offices with different IP address. When I connect to office1 it grabs the IP address right away but when I connect to office2 the IP address from office 1 does not release right away. I have to run winipcfg and release the IP address from office1 and then click renew all. I need to write a batch file to automatically does it for me.