Panel for selecting user groups

Hi All , 

I have Tab control . Please Find the below Pasted Screen Shots.

(1) User :   TabPage  

(2) UserGroups:  TabPage 

Please note that In [ User ] Tab Page .  I have selected a User [ADMIN]  and similarly

have assigned a group to the User [ADMIN] .

But My Requirement is when I select any another user  then in [USER GROUP]  under selected groups panel it should be empty so that I can assign any other group .

Please provide me code for this.

for your reference I am using the below code : 

void init()
{
#ResAppl

sysListPanel = SysListPanelRelationTableCallback::newForm(element,
element.controlId(formControlStr(Z_UserGroupForm, Usergroups)),
'@NIT139', '@SYS57280', #ImageUsergroups,
tablenum(UserGroupList),
fieldnum(UserGroupList, UserId),
fieldnum(UserGroupList, GroupId),
tablenum(UserGroupInfo),
fieldnum(UserGroupInfo, Id),
[fieldnum(UserGroupInfo, Id), fieldnum(UserGroupInfo, Name)],
0, '',
identifierstr(Validate), '', '');

super();

sysListPanel.init();
}

Regards ,

Nishath Salman