You can close your Roth IRA account without negative consequences if your total account balance is less than the accumulated amounts you deposited as regular contributions. Furthermore, if you distribute the total balance, you may be able to deduct the losses on your tax return.
For more information from the IRS on this matter, see "Recognizing Losses on Investments" in IRS Publication 590. (To learn more about retirement plans in general and the Roth IRA in particular, read A Tour Through The Different Retirement Plans.)
This question was answered by Denise Appleby