You can change this in several ways

1) Remove the feature

2) You need design and or contribute rights  (i forget the exact options) to have the k2 designer feature, so you can restrict user permissions by removing people from these groups

3) You can leave the overall icon there but you can restrict down access to all the wizards to specific SharePoint groups, therefore people could open the tool but only have access to functionality you decide is applicable.

hth