swap file delete

hello guys i need your help. i rooted my phone with an aim of increasing my phones RAM and i succeded. but my phone once got a problem and i lost the application ROEHSOFT RAM EXPLANDER which i used. it created a file worth 1.4gb called swap.swp on my sdcard. but now the problem i have is to delete the swap file as i noloonger have the application but whenever i delete it, i get a response some files can not be deleted but really i want my storage disk space back. is there any way i can delete the swap file? pliz help.