If we need to take time to cool off, we do so, but we don't avoid the issue. Discussing the problem is the only way to fix it. In many cultures it's common for children to live at home into early adulthood. For some families, having an adult child live at home isn't easy. For starters, set limits and clarify expectations.
Communication is key.
Sit down as a family and discuss how things are going to work. It's likely your child has changed, and you, as a parent, must change, too. If you feel a change in the rules is necessary, take into consideration your child's age, level of responsibility and any changes in lifestyle. Also, try rule-setting methods that worked for your family in the past. Likewise, if your child is used to a loose attitude toward household rules, continue along those lines.