Q. Delete or remove last line from a file.

This can be achieved  with SED command.

sed -i '$d' filename

Let me explain this command. SED is a stream editor which is useful for editing stream of characters. here -i option say's to insert the data in to the original file, ie modify original file. $ indicates last line and d for deleting that line and update to the file.

There are other methods to delete last lines

head -n -1 file1 > file2;mv file2 file1

Here I used head command to list all the lines but not the last line, redirected the output of this to a new file then moved file1 to file2.