downgrade composer version code example

Example 1: composer downgrade to version 1

sudo composer self-update --1

Example 2: upgrade composer version

composer self-update

Example 3: composer rollback to v1

composer self-update --1

Example 4: upgrade composer

To update composer command just find location of composer.phar and update as:
 where composer 	#Retrieves you location of your composer.phar
 cd path_to_composer.phar #Move to directory with composer.phar
 php composer.phar self-update	#Update your composer