寄 包裹去 上 海 怎 么寄 ？. 去。meaning in the sentence 寄包裹去上海怎么寄 ？ what is 去 grammar point. Is it a directional complement¿. Has it got the meaning of "in order to” Like in the sentence bellow after the definition. 

5 [between two verbal expressions, and / or after the second expression]

她上街去买东西了。(= 她上街买东西去了。= 她上街去买东西去了。) 
Tā shàngjiē qù mǎi dōngxi le. (or) tā shàngjiē mǎi dōngxi qù le. (or) tā shàngjiē qù mǎi dōngxi qù le.
She went to the market to do some shopping.

this another thing I found in dictionary. but is 寄 a verb of motion¿. And isn’t a 到 before 上海 ¿ if not how is it a preposition and a directional complement at the same time¿. I am confused. 

1 [after verbs of motion, indicating motion away from the speaker] thither; there; away

回家去 
huí jiā qù
go home

上楼去 
Shàng lóu qù
go upstairs

信寄去了没有？ 
Xìn jì qù le méiyǒu？
Have you sent the letter off yet?

And here what is the grammar point of 去

我会带他去几个有名的旅游景点比 如长城 、天 安门、. 

Thanks
In your examples, take 去 as to.

She went 'to' the market ("to" do some shopping): 她上街("去"买东西)'去'了 is a complete translation for the sentence, but wordy with two 去, so just dismiss any.

寄包裹去上海怎么寄: How to deliver the package "to" Shanghai

回家去: go home or go "to" the living place (no "to" as "home" is an adv here)

信寄去了没有: Have you sent the letter "to" (somebody) yet?
信寄出去了没有: Have you sent the letter "off" yet?

带他去几个旅游景点: take him "to" some tourist spots



Well, English uses different verbs for direction of actions, while in Chinese we use the same verb.

带他去上海: take him "to" Shanghai 
带他来上海: bring him "to" Shanghai

她买东西去了: she went shopping somewhere 
她买东西来了: she bought sth and brought here