GDPR gives individuals the right to have their personal data deleted, although this is not an 'absolute' right. If you still need to retain the personal data concerned, you may be able to refuse the request. Moreover, the right to erasure does not mean you erase all the data if you have a need and legitimate interest basis to process their data for audit records. If you cannot erase data (for example, there is a legal requirement to keep certain records for 6 years) then consider restricting the processing, such as moving to archiving.
The data minimisation principles should also be applied, together with an appropriate retention period. Ensure that you inform the data subject as to what data you are keeping.