command not found typically results from 2 cases:

1. an executable not having execute permissions for your user or group
2. an executable not belonging to a folder listed in PATH variable , or the opposite - PATH variable that does not contain the location of your executable.

As have been solved in the comments , your case is #2. For future readers, the solution is as such:

1. open your shell's configuration file in any text editor. If your shell is bash open ~/.bashrc , if your shell is zsh open ~/.zshrc. Note that ~ refers to your home directory.
2. Add line export PATH="$PATH:/usr/sbin" . Note, that /usr/sbin is just an example, your location might be different.
3. Save the file, exit and run source ~/.zshrc or source ~/.bashrc. Note, that for shells such as ksh or dash you will need to use . ~/.bashrc since source command is bashism and is not portable

I restarted docker using systemctl in place of service.

sudo systemctl restart docker