Well, with a little effort, I figured out a manual work around which is nothing but running an update command on sysfulltextcatalogs table. However, before I do that, I had to enable the updates for the current server by executing sp_configure for 'allow_updates' option. Long story short, following set of queries helped me update the path and eventually made it possible to drop the catalogues.
SELECT * FROM sysfulltextcatalogs
SP_CONFIGURE 'allow_updates', 0 GO RECONFIGURE WITH OVERRIDE GO
UPDATE SYSFULLTEXTCATALOGS SET path = 'D:\Microsoft SQL Server\MSSQL\FTData' WHERE ftcatid = 5