Do I have to omit or not "to" when it is with the possessive adjectives in this examples?
1. a) I'm goint to visit to my family. OR b) I'm goint to travel to visit my family.
2. a) I have to bath to my dog. OR b) I have to bath my dog.
3. a) We should send some messages to our friends by the cellphone. OR b) We should send some messages our friends by the cellphone.

There are some examples where native speakers omit the word (TO) when it is next to a possessive adjective but I don't know the reason... Could someone tell me the reason or key about omitting TO when it is next to a possessive adjective?

Question

Do I have to omit or not "to" when it is with the possessive adjectives in this examples?
1. a) I'm goint to visit to my family.   OR   b) I'm goint to travel to visit my family.
2. a) I have to bath to my dog.   OR   b) I have to bath my dog. 
3. a) We should send some messages to our friends by the cellphone.   OR   b) We should send some messages our friends by the cellphone.

There are some examples where native speakers omit the word (TO) when it is next to a possessive adjective but I don't know the reason... Could someone tell me the reason or key about omitting TO when it is next to a possessive adjective?

Answer

1.  I'm traveling to visit my family.
2. I have to bath my dog. 
3. We should send some messages to our friends.
The reason behind these has nothing to do with possessive adjectives. It is because of the verbs. 
For example: You need to learn how to bath a baby. 
Or: I'm travelling to visit some friends. 
Or: Please send a text message to me.

Answer

Be sure that you understand the different usages of "to"

e.g. I am going to visit my friend ("to" is part of the infinitive verb "to visit")
e.g. I am going to Brazil ("to" is a preposition of movement)

Many verbs of motion (but not all) are followed by a "to" and an indirect object
e.g. go, run, travel, walk.  You need to notice this when you learn a verb.

Sometimes the same verb is used also with a direct object 
e.g. I ran to the end of the street (indirect).  I ran a race (direct)