Deleting File which is displayed in picturebox

I am selecting file from openfiledialoge and displaying it in picturebox and its name in textbox when I click on delete button I am getting exception The process cannot access the file because it is being used by another process.
I searched a lot for this exception to get resolved but i didn’t fine any of them working, when i tried closing file with imagename which is in textbox i.e the file i am displaying in picturebox ; using IsFileLocked method,this closes and deletes all files of particular directory path ,but how can I delete the only file shown in picturebox,where I am going wrong