I was able to work around this, and will offer my own explanation of how to do it in case others have difficulty following the instructions already given, as I did. I'm using Evernote for Android 10.11 (1114563) with a Premium account.
Problem: When I shared something to Evernote, the new item was always assigned an annoying tag left over from a prior share. Here's the workaround:
Share something to Evernote from your Android browser.
At the bottom of the dialog that pops up, you'll see your annoying tag listed. Click it to get a full list of tags.
Search for the annoying tag, which will have a green check mark next to it.
Carefully tap the green check mark to unselect it.
Click Save to complete the share.
From then on, your default share will be set to No Tag.
Note that if you ever tag an item again in the share dialog, your choice will be sticky (aka annoying) until you repeat the steps above. There does not seem to be a way to create a real default tag for sharing--it always repeats prior selections. I work around this by never choosing a tag in the share dialog. I always share to a Notebook called _Inbox and assign tags in the Evernote app before moving items to the Notebook where they belong. You could do something similar by searching on "No Tag" to ensure that each item has only one tag.
That said, this is a bug and needs to be fixed.
