Viswas,
This is a pretty common operation, usually for the purpose of switching a dSource from an Oracle DataGuard primary to a standby, or from one standby to another standby, or from a standby to the primary. Please bear in mind that it is necessary that a detached dSource can only be attached to a source database with the same Oracle DBID.
There is a step-by-step walk-through in a "cookbook" recipe in the Command-Line Interface (CLI) section of the documentation
HERE. In this recipe, the CLI commands to first detach a dSource are described; this can also be done from the graphical interface using the "unlink dSource" icon. Then, the CLI commands to next re-attach the dSource to another source database in another source environment are described.
Whenever using the CLI, it is always helpful to remember to make heavy use of the tab-completion and tab-list-of-values functionality, similar to the UNIX/Linux BASH shell, in addition to knowing that
Hope this helps!
-Tim