How do I delete the list of cancelled / expired subscriptionsfrom the history on iphone ?

You can't delete subscriptions from your purchase history but you can hide them. See this document: Hide purchases from the App Store; click here --> https://support.apple.com/HT201322. Confusingly it only mentions hiding apps but according to Apple (as Recommended in: https://discussions.apple.com/thread/252760951 ) subscriptions get hidden too.