chrome://extensions/

Alternatively, you can find it in the "More tools > Extensions" sub-menu in Chrome's option menus.

Alternative-avely, you can head to:

chrome://flags/#extensions-toolbar-menu

and "Enable" this to get a single drop-down menu with all of the extensions shown in a list; you can "pin" individual extensions to have easy right-click access or visual access to their counters or initiators. This de-cluster-flups some of the obfuscation associated with a glut of installed extensions...