bash: /usr/bin/sudo: Permission denied

[hublex]

my plan was, making my life more easier. I do use a LTE-Router atm with limited data volume only. To not let any app entering the internet on my Ubuntu System and using my limited resources I was hoping to use use your app choose only a few apps which are allowed to enter the internet, like internet browser...
Now I am blocked using my system as usual, like opening my files on my cloud.
I neither able to open firejail for changing the settings, nor able to de install it.

failing to unistall:

sudo firecfg --clean
bash: /usr/bin/sudo: Permission denied

type into the terminal firejail and I get the following answer:

Warning: an existing sandbox was detected. /bin/bash will run without any additional sandboxing features
Error: --shell=none configured, but no program specified

Please help

[kmk3]

failing to unistall:

sudo firecfg --clean
bash: /usr/bin/sudo: Permission denied

type into the terminal firejail and I get the following answer:

Warning: an existing sandbox was detected. /bin/bash will run without any additional sandboxing features
Error: --shell=none configured, but no program specified

What is the output of the following commands?

firejail --version
which -a firecfg sudo
ls -l /usr/bin/sudo

[rusty-snake]

Wirst case recovery: Boot with init=/bin/bash (or maybe systemds rescue/emergency targets), remove all symlink in /use/local/bin pointing to firejail and chsh the shell of your user. If you use a SELinix system relabel on next boot.

Before doing anything of the above, read (arch)wiki and understand what the commands do.

[aritus007]

bash: /usr/bin/sudo: Permission denied

I did uninstall and reinstalled Firejail to have this issue resolved.

$ sudo firecfg --clean
$ sudo apt remove firejail
$ sudo apt purge firejail

The reinstall.