no.
you can't
You should be able to rename a Pokemon any number of times in the game.
Go into your computer to Bill's PC, and then to "Move Pokemon". When you click on the box, one of the options should be to rename it.
click on options then click rename
You can rename a pokemon by going to the Name rater
there is no such thing as the name deleter but there is a person in eterna who will rename your Pokemon and in canalave there is the move deleter.
In slateport city there is a name rater who can rename your Pokemon remember Pokemon traded to you can't be renamed.
In Eterna city where the second (grass type) gym is, go into the apartment block and on one of the floors there is an old man who will rename your Pokemon. He will not rename Pokemon that you got in a trade though.
Once you name your character, you can't change your name, unless you restart your game.
The Name Rater will rename any of YOUR Pokemon. If you own a Pokemon that originally belonged to someone else (Like the Machop you trade for in Goldenrod), then he wont rename it.
Go to the namerater in Lavender Town or rename it right after you catch it.
In Goldenrod city, there is a tent where the name rater is. Talk to him to rename your Pokemon. However, you cannot change the names of any Pokemon you have traded in or migrated from another game. You can purchase an Action Replay DS / DSi/ 3DS and change any Pokemon name even if its not your Pokemon under your Trainer ID.