void closeDBFfile(cdbfapiPlus* handle);

When you finish working with a DBF file you have to close it.

{
    cdbfapiPlus* dbf = cdbfapiCreate();
    if (!dbf) return;
    
    if (openDBFFile(dbf, "c:\\tmp\\example.dbf"))
    {
        // your code
        closeDBFFile(dbf);
    }
    cdbfapiRelease(dbf);
}