Contact them via email and explain to them. They will cancel your bid free of charge...
If it were SnapNames then it would be another story....
You MUST MEAN opposite, because Snapnames WILL lower bid, Namejet will not, they will not even lower PROXYBID (say current bid is $200, you made by mistake $2000 proxybid by mistake yet they will not lwoer it). Actually in Snapnames you can lower proxybid anytime without even asking.
I asked Namejet TWICE to lower just a proxybid (the bid was still low) both time rejected, this is genuine ticket:
Denny said:
Pls lower my ***.net bid to 170 the 1170 was typo why the system did not give warning ? And why can not lower bids as can in Snapnames ? It does not make sense, now the highest bid is $121 so why I can not lower it to $121 it does not make sense UNLESS its exacly your intention
Answer after 14 hours when the auction ended:
Lamejet said:
Hello Denny, thank you for contacting tech support. I show you won the auction with a bid of 452.00. The system doesn't allow you the option to lower a bid, so please in the future be careful of how much you are bidder for a domain.
OP just should fail to pay, that means change CC info to some card from which can not be charged more than few bucks.