Hi Mohanbabu M
It looks like you have deleted some of the components depending on the webapp in incorrect order of deletion. For example, VNet and subnet components has been deleted prior. In-order to fix the issue, I recommend re-creating the VNet and subnet using the same names, which will allows remove the webapp successfully.
Hope this helps.
--please don't forget to upvote
and Accept as answer
if the reply is helpful--