After many back and forth they finally figured out they would never "merge" the two. They did find they could delete the other partition then extend the size of the partition they needed to be bigger. The idea of merge was something from the days of Partition Magic which as far as I know is no more.
I installed windows 8.1 on my dell latitude 6400 after uninstalling windows 8 and ubuntu 14.04. Now the ubuntu partition of the hard disk is not getting merged with the disk containing windows 8.1. Due to this there's always an alert stating low disk space and necessary updates are not getting installed. Can anyone suggest remedy for this?