Just execute following command
sudo apt install composer
Installing process as like following
[sudo] password for saidul: Reading package lists... Done Building dependency tree Reading state information... Done ... ... Setting up composer (1.10.1-1) ... Processing triggers for man-db (2.9.1-1) ...
Now, check version which will ensure composer install successfully
composer --version
Output like
Composer 1.10.1 2020-03-13 20:34:27
you can remove composer using following command
sudo apt-get remove composer