Jestony,
This is basically what you what but you should apply some careful thinking before doing this.
gam print aliases > AllAliases.csv
AllAliases.csv will have the headers: Alias,Target,TargetType
TargetType will be User or Group
If you want to delete all aliases (think carefully) do:
gam csv AllAliases.csv gam delete alias ~Alias ~TargetType ~Target
If you're only trying to delete User aliases, edit AllAliases.csv, delete all lines that have TargetType = Group, save that file as UserAliases.csv.
If you want to preserve some user aliases, delete them from UserAliases.csv
gam csv UserAliases.csv gam delete alias ~Alias ~TargetType ~Target
If you want to get rid of some group aliases, edit AllAliases.csv, delete all lines that have TargetType = User, save that file as GroupAliases.csv.
If you want to preserve some group aliases, delete them from GroupAliases.csv
gam csv GroupAliases.csv gam delete alias ~Alias ~TargetType ~Target
Ross