Our disk space gets filled every month, is there is any way by which we can reduce it. As some of our queries & dashboard become redundant after sometimes, but there is no option to delete it from the interface

Redash automatically cleans up old query results to save your disk space. This is toggled on by default but controlled with the REDASH_QUERY_RESULTS_CLEANUP_ENABLED environment variable. It works by removing results older than a certain threshold, which defaults to 7 days but can be controlled by the REDASH_QUERY_RESULTS_CLEANUP_MAX_AGE environment variable.

How to check the value of those 2 variables in a Docker-based installation environment?

You will typically find these environment variables specified in a .env file at the root of the code. Else it may be specified under an environment key in docker-compose.yml. For installations based on one of our AMI’s it will be stored under /opt/redash/.env