You can access the package from SQL Server Management Studio.
1) Select ‘Integration Services’ in the connection option instead of ‘Database Engine’.
2) Expand Stored Packages – Expand MSDB and search for your package (With the same name which you used during saving the package.)
In order to manipulate the SSIS Package – You need to right click on it and Export to a .dtsx file and Open the DTSX file in BIDS / SQL Server Management Studio.
After modification – import the package again to MSDB database by right clicking on the MSDB folder in SSMS (Integration Services) and selecting Import Package option.