If you have duplicate/outdated lead profiles, you can easily merge them profiles on your admin dashboard.
Navigate to the People main menu on the left side of the screen and head over to the Leads page.
Select the lead profile that you'd like to merge by clicking on the 3 dot button on the right side and then select Merge.
On the pop-up, select the duplicate profile by clicking on the + icon inside the Select duplicate box.
Type the duplicate profile's name and select the same. Additionally, you can click on any of the two boxes in the pop-up to make it the primary profile.
Alternatively, click on Bulk Select and select the profiles that you'd like to merge by checking the boxes on the left. Click on the Merge Leads icon (to the left of the Bin icon). On the pop-up, select the profile which you want to make the primary profile.
Lastly, select the checkbox on the bottom left corner of the pop-up to confirm the lead merge and click Save.
(The duplicate lead profile will be deleted upon merging and their data will be transferred to the primary account)