I want to remove Magnetic Lasso Tool from shortcuts. Is this possible?

You have several options, with probably the best being what Bob has suggested, and that is to remove the Magnetic Lasso from your Toolbar.  If you do this, then note the Disable Shortcuts for Hidden tools checkbox at the bottom of the Customize Toolbar window.  I remove both Magnetic and Polygonal Lasso Tools because the plain vanilla lasso tool works like the Polygonal lasso tool by using the Alt/Opt key.

You can also remove the shortcut from the left side of the window by hovering and deleting.  When I hit the B key I always want the normal brush tool, for instance.  I almost never use the magic Wand tool so I have removed its shortcut.  That all saves time.  Note also, that I always turn off using the Shift key to toggle between tools whith the same shortcut, because I can think of no reason to use two keys when one works just fine.

You can also remove shortcuts in the Edit > Keyboard shortcuts panel.

What makes this really powerful is that we can save custom shortcuts with custom workspaces.  This means you can reassign shortcuts, and if you want the defaults, switch back to the Essentials workspace.

To make this work as seamlessly as possible I use simple Actions that set and reset workspaces, and trigger them with function keys.  It's very satisfying to completely mess up your workspace — something we do a lot for taking screen shorts for forum answers — and have tidied up with the press of a single key.

I like to point out that the defualt Function key shortcuts are only useful if you have a tiny notebook type screen IMO, so can be used to trigger actions, or those annoying funtions hidden in right click menues like Make Smart Object and rasterize.