You are not required to use HXTT driver with Teiid. Yes, if you use HXTT you will see the metadata wrt to that JDBC driver. To work with Text files in Teiid, take look at one of examples here Hello World Teiid Data Federation Example - Teiid Examples - Project Documentation Editor
See the MarketData model reading the text file in this example.
I have go through the link, one thing I am not able to figure out is can we access remote file by setting some properties in resource-adapter which we created for files? or is there any way to access remote file by using sftp and ftp protocol.
I use this kind of resource through the Teiid server filesystem, eg: mount the remote file path somewhere, and make Teiid access that file as if it was local... (depending on performance, you could try to cache access to this file, in Teiid)
About HXTT driver issue, could you perhaps try to change permissions to make it only reach the file you need it to return the schema for?