How to remove the picture next to my name in gmail
The picture is linked to the google+ profile. When YouTube switched to g+ for comments, existing YouTube accounts were basically converted to a limited g+ profile. So, you may actually have more than one g+ profile. 

Go to Google+ on the computer. Trust me it will be easier than the mobile site or the app. In the upper right corner, click on the picture or icon that is there. You should see the g+ profile you created and below it your YouTube profile. 

If you are already on the profile with the picture, click on the "change photo" banner that appears over the profile photo. 

If you aren't on the profile with the picture, click it to switch to that profile. Then click the picture in the upper right again and click the "change photo" ribbon over the picture. 

Now you can change the photo to whatever you want or just upload a generic or even solid color picture. I don't know of a way to completely delete it, so maybe just upload an all white box instead.