Hi Gokul B ,
Welcome to Microsoft Q&A platform and thankyou for posting your question here.
As per my understanding , you want to know that in order to create a new IR and delete the older one , do you need to remove the GIT integration with the ADF or not. Please let me know if there is any gap in the understanding.
There is no need to remove the GIT integration with the ADF. All you need to do is to create the New IR in a local branch and then merge it to the master branch by sending out the Pull request.
It should work the same way you create any other resources in ADF.
Hope it helps. Kindly accept the answer by clicking on Accept answer button. Thankyou.