[SOLVED] How to unplug this cable connector

[dalocs7]

I'm trying to unplug the white plastic connector in the image but it just won't come out. I've tried with my hand and with pliers. Does it have some lock or should I just pull out with more force? Any ideas?

https://imgur.com/a/nMiq9be

 

[geofelt]

I see 4 white connectors.
It looks to me like they might have a latch.

I often have trouble removing the 24 pin psu connector.
I find it helps to use a thin screwdriver between the seams to pry the connector up