To change the Grace tcsh prompt, edit the .cshrc.mine present in your home directory by adding the line below. Remember to log out and log in again to see the effect. You can also run source .cshrc.mine to see the effect without having to log out.
set prompt = '[%n@%m %c] '
%n represents your name (directory id), %m the hostname (up to the first period) and %c the last directory part. The above will set the prompt to [nelson@grace5 ~] when user nelson is in the home directory of grace5. The prompt [nelson@grace5 ~/216public] will appear when the user is on the 216 public account. You can remove any of the options above.
Check https://www.cs.umd.edu/~srhuang/teaching/code_snippets/prompt_color.tcsh.html if you are interested in adding colors to the prompt.