i want to eliminate 'user John' as default download location

I want to eliminate 'user John' as author of my pdfs.
i want to eliminate 'user John' as default download location
i want to eliminate 'user John' altogether from my machine.

-how do i do this ?

thanks, so much, for anyone that can give step-by-step instructions

mac
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Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft® Windows Vista™ Home Premium, Service Pack 2, 32 bit
Processor: AMD Turion(tm) 64 X2 Mobile Technology TL-60, x64 Family 15 Model 104 Stepping 2
Processor Count: 2
RAM: 3453 Mb
Graphics Card: ATI Radeon X1200, 128 Mb
Hard Drives: C: Total - 151122 MB, Free - 66638 MB;
Motherboard: ATI, SB600
Antivirus: avast! Antivirus, Updated and Enabled