# first make sure where is the npm installed
$ which npm
# output: /home/sallo/.nvm/versions/node/v14.15.3/bin/npm

# now open the file ~/.zshrc and add the below line at the end.
# change the path in cause you have different

export PATH=$HOME/.nvm/versions/node/v14.15.3/bin/npm:$PATH

# save the file and open new terminal