Your title mentions SGW - what is this?
If you call the Officer list endpoint (for a given company) you'll get the officeList resource. This will return the information for each officer but there isn't a specific "identifier" associated with each officer record here. Essentially there's no unique ID because this dataset (or our access) doesn't link them to something else. (If you need some kind of unique ID yourself to organise things there's nothing to stop you creating one yourself but obviously it's down to you to map this and avoid clashes etc.)
However that's not quite the end of the story because in the "links" section of each item (officer record) there should be an "officer" section with "appointments". This holds the something like e.g.:
Call that endpoint in Companies House API and it will show you appointments for that officer. So the "
Rcye6xfT35E0SeA3Keyy-HLeLzU" bit is kind of an ID - but for the officer appointments "dataset", not the officer list one. (Caveat - I have no idea how things work behind the scenes and how Companies House store and link their actual data - so I'm using "dataset" and "link" loosely e.g. may or may not be the same actual data).
Be wary about "IDs" as you'll find the metaphor can be quite limited. For example there's an Officer Disqualifications endpoint - but Companies House have stated that this is separate from the Officer Appointments / Company Officers "dataset".