URGENT: Request to cancel skilled worker visa

[DRMSA]

Hi
I need an urgent advice please.

I had a COS for skilled worker visa for my first job in the UK to apply from outside the UK.
COS expiry date is 2/6/2024.
I applied from outside as a standard "not priority" on 27/5/2024, and paid to keep my passport with me.
For family condition I need to gave up from the job and cancel my visa.
I had applied on UKVI for application cancellation on 2/6/2024, but an hour later I have received an email with Visa application is successful letter with a date of 30/5/2024, and asking me to waiting until visa center contact me.

My questions:
Are there any chance for my cancellation request to be accepted now?
If cancellation request was not accepted, can I ask my employer to cancel it?
Would be any consequences or penalties on me if the visa is cancelled after being issued?

Thank you in advance