For this section :https://prnt.sc/vzm4fp
Please use below code in custom css
.login_popup{
background-color:aliceblue;
}
.login_popup .login_popup_content{
color: #ece0e0 !important;
}
.login_popup .login_popup_content h2{
color:white !important;
}
.login_popup .loginform label .forgot_password{
color:#f7eb56 !important;
}
For this Part -
https://prnt.sc/vzmk69
I could not understand why you said to remove so I have provided code for both changing the color as well as removing
Use as per your need
.login #login h1 a {
width:360px !important;
height:120px !important;
}
/* If you want to remove the register/lost your password section */
.login #login #nav, #backtoblog{
visibility:hidden !important;
}
/*For changing background color*/
.login{
background-color:#d8d7d7 !important;
}
/* For changing the font color of register|lost you password*/
.login #login #nav a, #backtoblog a{
color:#5b6060 !important;
}