Are you able to send larger photo files? Unfortunately these are too small for us to see any detail. The first photo appears to show just lichen, a normal and harmless growth on many kinds of tree bark, and which does not need removal. Is there a particular symptom that you are concerned about? The tree pictured appears to be in good health from what we can see.

There are several ailments that can affect crapemyrtle, but it is no more or less vulnerable to its afflictions than other plant types are to their own set of pests or diseases. Examples of pests affecting crapemyrtle include Crapemyrtle Aphid (which usually does not need controlling) and Crapemyrtle Bark Scale. Examples of infections affecting crapemyrtle include powdery mildew and a type of leaf spot (Cercospora), neither of which tends to need intervention either. (Especially since pesticide use could harm pollinators or other beneficial insects.)

Occasionally either a cold snap in winter, drought coupled with a cold snap, or other factors can cause crapemyrtle branches or entire stems to die off over the winter, but this is not treatable and, if it happens, all that can be done is to trim off any dead wood that does not leaf-out with the rest by late spring. That does not appear to be the case for the plant in the photos, however.

Miri