To delete everything in a file with Vim, use this command.
- gg go to the first line
- dG delete to the last line of file (G is movement which is " go to the last line of the document ")
You can also apply this grammar by replacing d with something else. For example
- gg=G auto format file
- gggUG make all text in file upper case.
- ggVG select all text in file