You may either: -
a) Determine how much you are eligible to contribute to the Roth, leave that portion in the Roth and recharacterize the difference to your traditional IRA- or distribute the difference as a return of excess contribution or
b) Recharacterize the full amount representing the contribution to your traditional IRA ( or do a return of excess contribution for the full amount
The amount you recharacterize or remove as excess must take into consideration the loss.
This IRS document ( see link below) explains how to determine the loss/earnings on a particular contribution.
http://ftp.fedworld.gov/pub/irs-drop/n-00-39.pdf