Add-ins are plug-in like component installed to provide custom or new features for Office products. If you want to remove an already installed add-ins from Outlook 2010 in Outlook 2013, then you can do the following
Click the File menu –> select Options link and navigate Add-ins screen
Select COM Add-ins in the Manage drop down and click the Go button.
This would display the following COM Add-ins window. This can be used for adding or removing any installed add-ins. To remove any add-ins, un mark the check box against the relevant add-ins and click the OK button.
Also See: How to enable a disabled add-in in Excel