I'm not exactly sure what you mean by "uploaded photos", but regardless - in the stock Gallery application, just navigate to the category/folder/grouping that contains the pictures that you want to delete; press the Menu button; choose "Select item"; then tap each picture that you want to delete (you'll see the count of the number of items you've selected in the top bar); then select the Delete icon in the upper right (the little trash can). You'll be prompted to confirm that you want to delete them.
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