I can't cancel my Lightroom subscription on my phone. I checked the Adobe website and the Google Store but couldn't find an option to cancel my subscription. Please help me.

In this forum, we cannot cancel your subscription. You have to contact Adobe. I don’t know why you said you couldn’t cancel by phone or live chat, because you certainly can.

Contact Adobe support by clicking here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
In the chat field (lower right of screen), Typing “Agent” into the chat text field will bypass the initial chatbot. Be patient, it can take quite a while to reach a human. If you are not able to get to the chat window, then disable your ad-blockers, firewall, enable cookies/scripts on your browser. If it still fails then change your browser/machine/network.

Also, you can go to account.adobe.com, then login and cancel your plan. Here is what I see when I go to account.adobe.com and login.