Salesforce delete record: 'Insufficient privileges' error

In some organisation, user allow to delete records, but sometimes user get error message 'Insufficient privileges' although Delete button exist. What's happening? Let us analyze:

1. User able to access the record
There are few scenario:

• Organization-Wide Defaults sharing setting on that object is Public Read Only or Public Read/Write; or 
• Sharing rule added based on record owner or criteria for Public Groups or Roles; or
• User is the owner of the records; or
• User in higher role hierarchy of record owner; or
• User profile have "View all Data" or "Modify all Data" permission

2. User see Delete button
This is happened because:

• Delete button is added in record page layout; and
• User profile have permission to delete that object

3. Error 'Insufficient privileges' 

The ability to delete records in Salesforce is controlled by the role hierarchy. Setting a sharing model to "Public Read/Write" alone does not give users the right to delete others records. There are 2 scenarios in which a user can delete a record:

• The user attempting to delete the record is a System Administrator.
• The user attempting to delete the record is the owner, or higher on the role hierarchy than the record owner.

Any other user that attempts to delete a record will receive an "Insufficient Privilege" error message.

Those below you on the role hierarchy may have read/write privileges according to the sharing model rules, however, they may not delete information from those individuals above them in that hierarchy. 

For complete knowledge from Salesforce, click here.