Is it possible to purge old builds from the build history. We have no need to keep history older than a month, I thought storing the logs in a user created bucket would help, but this only affect the logs themselves not the history
With Google Cloud, there are no charges associated with storing build results. Your build history is permanently preserved within your project unless the project is deleted and the history is cleaned up by Wipeout.
You can check this document for pricing: https://cloud.google.com/build/pricing
It looks like as of now there is no option to delete build history.And if you have project requirements, you can raise a feature request under public issue tracker