Legally, no. However, the police may try to use their authority to bully you into erasing the videos or photos you’ve taken. You do not have to give in to these commands.
The police cannot simply grab your phone and delete the recordings themselves. Such actions would be a blatant violation of your Fourth Amendment rights.
They may have the authority to temporarily seize and search your phone after securing a search warrant. Even in these instances, however, it would be illegal for the police to alter or delete any of the files on your smartphone.