You can easily rename your dataset through the BigML API or using the Dashboard. For the former please read this subsection of the documentation for developers. For the latter, just select the dataset you wish to rename and click the More info menu option (see image below). Under the info panel click the edit icon and type a new name, select a category to classify your datasets, add a description, and some tags. This will let you, and other BigML users, quickly find the datasets published in the gallery.