kazulog@sv1:~$ cat /etc/os-release | head -2
PRETTY_NAME="Ubuntu 26.04 LTS"
NAME="Ubuntu"
kazulog@sv1:~$ sudo update-inetd --disable telnet
kazulog@sv1:~$ grep -n telnet /etc/inetd.conf
23:#<off># telnet	stream	tcp	nowait	root	/usr/sbin/tcpd	/usr/sbin/telnetd
kazulog@sv1:~$ sudo ss -tlnp 'sport = :23'; echo "ss rc=$?"
State                  Recv-Q                  Send-Q                                   Local Address:Port                                   Peer Address:Port                 Process
ss rc=0
kazulog@sv1:~$ sudo apt purge -y inetutils-telnetd | cat
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Reading package lists...
Building dependency tree...
Reading state information...
Solving dependencies...
The following packages were automatically installed and are no longer required:
  inetutils-inetd  tcpd  update-inetd
Use 'sudo apt autoremove' to remove them.

REMOVING:
  inetutils-telnetd*

Summary:
  Upgrading: 0, Installing: 0, Removing: 1, Not Upgrading: 96
  Freed space: 184 kB

(Reading database ... 91438 files and directories currently installed.)
Removing inetutils-telnetd (2:2.7-2ubuntu1.1) ...
Processing triggers for man-db (2.13.1-1build1) ...
(Reading database ... 91429 files and directories currently installed.)
Purging configuration files for inetutils-telnetd (2:2.7-2ubuntu1.1) ...
kazulog@sv1:~$ sudo apt autoremove -y | cat
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Reading package lists...
Building dependency tree...
Reading state information...
Solving dependencies...
REMOVING:
  inetutils-inetd  tcpd  update-inetd

Summary:
  Upgrading: 0, Installing: 0, Removing: 3, Not Upgrading: 96
  Freed space: 361 kB

(Reading database ... 91429 files and directories currently installed.)
Removing inetutils-inetd (2:2.7-2ubuntu1.1) ...
Removing tcpd (7.6.q-36build2) ...
Removing update-inetd (4.54build1) ...
Processing triggers for man-db (2.13.1-1build1) ...
kazulog@sv1:~$ dpkg -l | grep -E "inetd|telnet|tcpd" | cat
rc  inetutils-inetd                         2:2.7-2ubuntu1.1                           amd64        internet super server
ii  inetutils-telnet                        2:2.7-2ubuntu1.1                           amd64        telnet client
ii  tcpdump                                 4.99.6-1                                   amd64        command-line network traffic analyzer
ii  telnet                                  0.17+2.7-2ubuntu1.1                        all          transitional dummy package for inetutils-telnet default switch
rc  update-inetd                            4.54build1                                 all          inetd configuration file updater
kazulog@sv1:~$ ls -l /etc/inetd.conf 2>&1
-rw-r--r-- 1 root root 1062 Sep 12 09:15 /etc/inetd.conf