They should be easy enough to remove, just be sure to replace them with something. If you like versatility, having all your players get something like the paragon multiclassing should work. If not, you'll need powers for all the classes, my advice would be to lift them from some of the existing PP powers rather than trying to design your own.
I would use Paragon Multiclassing as basis, but instead of picking powers from your multiclass, you pick powers from your regular class.
Action Point features can come in different ways, and it might be covered by adding new options for APs anyway. If in doubt, there are some new Action Point enhancing feats from Dragon now that might fill that role. A feat I remember allows you to spend a healing surge together with an AP for example.
Epic Destinies... They have very varied effect. The simplest aspect is allowing the 26th level utility to be any 22 level utility from your Class or Multiclass.
Other generic stuff mght be:
21st level: +2 to two ability scores
24th level: Once per day if you die, recover half your hit points and stand up.
30th level: Pick one Daily Attack Power that you know. It is now a Encounter Power
I think the paragon paths and epic destinies itself are certainly needed in that they give important abilities that are part of the balance. But you don't have to use the specific implementation that 4E uses.
Action Points in a way work like an extra encounter power you get every 2 encounters. At Paragon with Action Point features, they turn into an extra daily power every 2 encounters, I think. The "lone" Action Point without any riders is essentially like a minor action (or actually a free action) encounter attack power, with feats and paragon features, it gets stronger than that.
Paragon Paths powers are essentially regular class powers with different constraints. One thing to understand is: You buy the entire package with paragon pathes and epic destinies. You can't cherry-pick like you might do with 3E Prestige Classes. So the overall package will be balanced, but not every path power and path feature against each other.