Vim – Convert text to uppercase or lowercase

Convert all the letters in the file, from the second line to the last line, to uppercase
:2,$s/[A-Z]/\U&/g

…and to lowercase…
:2,$s/[A-Z]/\L&/g

Vim – Find ascii code … replace ascii code

In command mode press the keys ga (like get ascii) to find out the ascii code of the character where the cursor is.

To do a search and replace with an hex code

:%s/\%x0d.*$//d

Being 0d the ascii character found with ga