Alias has become index after restarting elastic search

I restarted ES server on all my 3 nodes after installing delete-by-query plugin. However, after that I see that the aliases which were defined have become indexes. Due to this on restart I get error that "index and alias names should be unique" since that name is an alias as well as an index now.
ES doesn't allow me to delete alias as well. Hence, I am stuck due to this.

One of the nodes is up and other 2 can't be restarted due to the given problem.
The problem is same as given below:-