How does one get an obsolete town name removed

To get an official place or feature name changed, added, or removed, you'll have to submit a proposal to the U.S. Board on Geographic Names. You can find more information on the GNIS website http://nhd.usgs.gov/gnis.html#submit_webforms and the U.S. Board on Geographic Names website http://geonames.usgs.gov/

Here's some information from the BGN FAQ page:

"Proposals to name an unnamed natural feature may be submitted to the U.S. Board on Geographic Names as described below. The Board is responsible by law for standardizing geographic names throughout the Federal Government, and promulgates policies governing issues such as commemorative naming, derogatory names, and names in wilderness areas. Generally the most important policy is local use and acceptance."

"Upon receipt of a proposal, all interested parties will be asked to comment. The Board makes decisions only after receiving recommendations from the local government, county government, the State Names Authority (in 50 States, the District of Columbia, and 2 Territories), and appropriate land management agencies. Only name proposals for natural features will be accepted (see FAQ #7 for information on administrative feature names—churches, cemeteries, schools, parks, shopping centers, etc)."

"A new name proposal may be submitted using the Domestic Geographic Names form (PDF version) mailed to U.S. Board on Geographic Names, U.S. Geological Survey, 12201 Sunrise Valley Drive, MS 523, Reston, VA 20192-0523. Alternatively, the online version of the form may be used. Please read the Principles, Policies, and Procedures in the Main Menu to the left before submitting a proposal. An information packet and forms can be mailed upon request. The entire process is free of charge, but will take approximately six months. For more information contact the GNIS Manager."