Hi there,
Even though you don't have that page, Google is still indexing it, because it returns a 200 status code - it doesn't 301 to the lowercase version. This means that even though you haven't created it, the website is still returning /SERVICES/ as individual web pages, separate from the lowercase ones. Even though the URL seems wrong to you, to Google, they're being told by the website 'hey, you should index these /SERVICES/ pages', due to the 200 status code.
Using the canonical you suggest would tell Google that the subfolder they should index is SERVICES. This would mean Google would drop (if it follows the canonical rule correctly) all lowercase iterations of /services/ and instead index /SERVICES/. So therefore, you do not want to add a canonical with /SERVICES/, as this would not get rid of /SERVICES/, it would tell Google that **this (/SERVICES/) is the version you want indexed. **
You should add a canonical tag to all of your /services/ pages indicating that the correct canonical version is /services/ - with the lowercase. This should then propagate to your /SERVICES/ pages, indicating the version you want Google to index is the lowercase version; this will get rid of /SERVICES/.
Alternatively, if this isn't clear for you, I would recommend you set up a 301 rule to redirect all versions of /SERVICES/ to /services/.
Hope this helps.