Good question! No, currently not.
There are two things to look at:
1) The Maxmind file that was downloaded by the “Automatically download DB”-source (located by default at uploads/GeoLite2-City.mmdb) should be deleted
2) The Web-based sources (hostinfo, precision) are using wordpress transients to cache the results locally.
-> 1: I could delete the file on uninstall. This will only work if the plugin is being deleted in the backend, not on the FTP side (so I cannot guarantee its execution, but that’s ok.) – Will be in the next release of the plugin.
-> 2: Deleting transients is difficult because there is no wordpress API for this. (You could delete them in the database but not all installation are using the DB backend of transients.) Also, they are temporary by nature and will expire after 2 weeks (by default), so wordpress will delete them some time after that. – I guess that’s a “won’t fix”.
