@Thadani, Sanjay (Cognizant) Thanks for reaching out. The FHIR service currently doesn't support conditional delete as part of transaction bundles. I do see this is not mentioned in our documentation, which is a gap on our end. I will pass on the feedback to our docs team about adding this note in our documentation.
We apologize for the inconvenience caused. you can use batch bundles instead of transaction bundles that supports conditional delete.
I hope this answers your question and feel free to add a comment if you have any other questions. We would be happy to assist you. Please 'Accept as answer' and ‘Upvote’ if it helped so that it can help others in the community.