You don't say which OS you are using.
The left hand side lists recently used programs, plus a couple which are displayed by default. You can't freeze the list, but you can limit it to only a few items.
If you right click on a blank bit of task bar and select properties you should get the Start Menu properties.
Click the tab for start menu, then click customise.
Set the number of programs to a lower number or zero.
Then click Advanced, and select those features you always want displayed. Click OK, OK.
Alternatively you could switch to Classic Start Menu.