How to remove icon from left corner of the screen ?

In Widget, you could have activated Siri Suggestions.

If you don't wanna see that icon, try to disable that widget and turn your device off and back on. The icon in the bottom left corner should disappear.

Regards

Giulio

This is part of the "Handoff" feature which allows you to seamlessly move to your iPhone when using an app an your Apple Watch. For example, you can check your email but not reply to emails from your watch. If you are checking an email on your watch and want to reply to a message, you can simply swipe up on the Mail icon in the lower-left corner of my iPhone Lock screen to quickly access that message and type your response. The icon on the Lock screen will match the last app you were using on your Apple Watch.

You can disable Handoff on your Apple Watch by opening the Apple Watch app on your iPhone, then navigating to >My Watch > General > Enable Handoff.

You can also try this steps

1. Open the Settings app on your iPhone or iPad
2. Go to “iTunes & App Store” and scroll all the way to the bottom
3. Under ‘Suggested Apps’, toggle the switches for “My Apps” and “App Store” to the OFF position
4. Exit Settings as usual