According to info from LinkedIn's Help Center: "It's not possible to remove a connection from a mobile device."
Here is the content they share related to your issue:
To remove a connection from the desktop:
- Go to the connection's profile.
- Move your cursor over the Arrow
icon next to the button in the top section of the profile. The button
name may vary.
- Select Remove connection.
- Review the list of
effects of removing the connection and click Remove.
Note: If you don’t see Remove connection in the drop-down list, you
may need to refresh your connections. To do this, go to your
Connections page, click the Settings icon on the right, then click the
Refresh link next to LinkedIn.
You can remove several connections at once on the Contacts page:
- Move your cursor over Connections at the top of your homepage and
select Keep in Touch.
- Click Filter by and select Connections Only.
- Check the box next to the connections you'd like to remove.
More above the first connection and select Remove from Contacts.
- Review the list of effects of removing the connections and click
You can also remove individual connections from the Contacts page by
clicking More under their name and selecting Remove Connection.
Connections you remove will no longer be a 1st-degree connection and
will no longer appear in your Contacts section.
- When you remove a connection, they won't be notified.
removing a connection, any recommendations or endorsements between you
and that person will be withdrawn. They will not be restored if the
connection is re-established.
- Only the member who breaks the
connection can reinitiate that connection.
Find the original info source here: http://help.linkedin.com/app/answers/detail/a_id/49/~/removing-a-connection