Hi Alankrita,
I presume ‘entry for nodes’ means Adapter connection name in Adapter Settings tab you are referring to. I didnt get exact meaning of ‘Removing entry’. Below are few pointers to change that 3rd node to point to 2nd connection:
1.Use ART service wm.art.dev.service:updateAdapterServiceNode to point to 2nd connection.
2.Delete unwanted 3rd connectiion from IS.
3.Cross check whether services are working fine.
I might be oversimplifying the scenario. Provide more details if possible.
Cheers,
Niteesh 
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