Here is what you can do:

1. In the Server Administrator, go to "Corporate settings >> Fields" and create a new field, Type: checkbox, name: Inactive freelancer.
2. Go into the "custom fields" tab of each freelancer you want to disable in the list, and check the new field.
3. Click the asterisk in the upper-right corner of the table and enable the "inactive freelancer" column.
4. (optional) Create a filter with a condition "Inactive Freelancer equals 1".