Yes, it is allowed. Sometimes it is even necessary to photoshop out logos.
However, your photoshopping should be subtle, so that your picture not appears to be photoshopped. And photoshopping should not introduce artefacts.
Thanks..but don't you think that this will affect its originality?
People buying stock aren't bothered about originality, and people selling stock aren't trying to win photography
competitions so yes, of course you should use Photoshop, as long as it isn't obvious.
love who easy the photoshop program works