Easy way to enable the Telnet client in Windows 10, also in Windows 8 and Windows 7. by using the command line/command prompt and write or paste the following command:
pkgmgr /iu:"TelnetClient"
To open Command line/ command prompt, press Windows+R then type cmd, klick OK or hit Enter.
Write or paste the command: pkgmgr /iu:"TelnetClient" into the command line.