@Aginash Mannarath Thank you for reaching out to us, As I understand you are looking for steps to restore the delete enterprise app.
Refer to the below articles
https://learn.microsoft.com/en-us/graph/api/directory-deleteditems-get?view=graph-rest-1.0&tabs=http
Which has the steps to restore the service principal via Graph explorer/permissions required to perform this operation.
Let me know if you have any further questions, feel free to post back.