How to Remove a Line Using CFile class in MFC

what do you want?
remove a certain text in file or a line?
if you mean a line, do it :
in a loop write lines until you arrive to that.
then read that line but don't write.
after that in a loop write remainder lines.

CFile f;
f.Open(_T("path of the file"),CFile::modeRead|CFile::modeWrite);

read function is :
f.Read(buffer,count);

write function is:
f.Write(buffer,count);

f.Close();