You cannot rename existing shared parameters or change their type, but you can move them to a different group or delete them.
You can do the following:
Click Manage tabSettings panel (Shared Parameters). In the Edit Shared Parameters dialog, select the parameter from the Parameters pane and click Properties from the Parameters group box.
Click Manage tabSettings panel (Shared Parameters). In the Edit Shared Parameters dialog, select the parameter from the Parameters pane and click Move from the Parameters group box. Choose another group from the menu and click OK.
Click Manage tabSettings panel (Shared Parameters). In the Edit Shared Parameters dialog, select the parameter from the Parameters pane and click Delete from the Parameters group box.