For your references, the issue was already been resolved by the following procedure below. please refer on this link for references.
1.Click Start, click Run, type ADSIEdit.msc, and then click OK
2.Expand the Domain Naming Context container.
3.Expand DC=Your Domain, DC=COM
5.Right-click the Trust Domain object (childDC. domain.com), and then click Delete
7.Right-Click CN=Users--> CN=child domain$ and then Delete. If not deleted (no problem follow next step)
8.Go to ADSI edit in administrative tools
9.Right click ADSI Edit ->connect to Domain's Naming context" configuration" then click ok
10.Cofiguration-->CN=configuration,DC=your domain,DC=com -->CN=Partitions
11.Select and Delete Name: CN=your child domain /Directory partition Name: DC=child domain,DC=com
12.Now check Active Directory Domain and Trust (child domain entry would be removed)