Hi @Abhishek Singh ,
it's not possible to block the inheritance of locks in Azure.
You need to remove the lock at subscription level and add the lock on resource group level.
There is a feedback at Azure Feedback. You can vote for this feature request if you like:
https://feedback.azure.com/forums/281804-azure-resource-manager/suggestions/34383535-ability-to-disable-lock-inheritance
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Regards
Andreas Baumgarten