Using version 2.0.2, seeing same results with 10.9.5 and 10.10.5, running CLI or through policy
administrator$ dockutil --remove '/Applications/Microsoft Office 2011/Microsoft Excel.app' --allhomes
item /Applications/Microsoft Office 2011/Microsoft Excel.app was not found in /Users/administrator/Library/Preferences/com.apple.dock.plist
also tried just using
administrator$ dockutil --remove '/Applications/Microsoft Office 2011/Microsoft Excel.app'
It does exist in the plist and I tried different combinations of ' ' and to deal with spaces
<string>com.microsoft.Excel</string>
<key>dock-extra</key>
<false/>
<key>file-data</key>
<dict>
<key>_CFURLAliasData</key>
<data>
AAAAAADUAAMAAQAA0QwbhgAASCsAAAAAAC0M
+AA4/4oAANE4DXAAAAAACSD//gAAAAAAAAAA
/////wABAAgALQz4AAAAGgAOACgAEwBNAGkA
YwByAG8AcwBvAGYAdAAgAEUAeABjAGUAbAAu
AGEAcABwAA8AGgAMAE0AYQBjAGkAbgB0AG8A
cwBoACAASABEABIANkFwcGxpY2F0aW9ucy9N
aWNyb3NvZnQgT2ZmaWNlIDIwMTEvTWljcm9z
b2Z0IEV4Y2VsLmFwcAATAAEvAP//AAA=
</data>
<key>_CFURLString</key>
<string>file:///Applications/Microsoft%20Office%202011/Microsoft%20Excel.app/</string>
<key>_CFURLStringType</key>
<integer>15</integer>