Toad 14 beta cannot affect 13.3 or 13.2. Something else must have changed at the same time.
Possibly related: Toad 13.2 and prior will give an "Invalid Oracle Home" message if instant client files has the DLLs in a subfolder named "bin" (this is not the default configuration)
Note: There may be some junk in the registry that needs to be cleaned out after deinstall. See Cannot load OCI: C:\Oracle\product\12.2.0\client_1\BIN\OCI.dll