Myst supports the ability to remove resources known to Myst.
You can remove a resource by adding a MyST Extension attribute to the resource.
For example, if you want Myst to delete the JDBC DataSource called Stock Trader.
Go to JDBC Data Sources > StockTrader
Click Show advanced properties
Scroll down to MyST Extension and add the attribute
Click Save and Commit
Running a Myst 'update' action will now delete the DataSource